The present invention relates generally to instantaneous water heaters, and more particularly, to an improved control system in a water heating and delivery system which enables the quick and accurate heating of water to a selected set point temperature.
Instantaneous hot water heaters adapted to service one or more water outlet taps are well known, as shown in U.S. Pat. Nos. 3,099,737 and 3,952,182. The instantaneous water heaters disclosed in these patents, although adequate, fail to provide optimum user control to insure that the temperature of the water being discharged from the tap corresponds to the demand set point temperature established in the control system. Such precision is especially important for those people who are insensitive to temperature. An excessively high water temperature may damage skin tissue of a person afflicted with such a condition, and yet, the person exposed to such hot water will have no sensation of pain.
Most instantaneous hot water heaters employ on and off switching controls which operate in either a full "on" mode or a full "off" mode, depending upon the sensed temperature of the water being discharged with respect to the selected set point temperature at which the water is to be discharged. When the temperature of the water being discharged is below the set point temperature value, full power is applied to the heating elements, and when the temperature of the water is above the desired set point temperature, there is a complete absence of power being supplied to the electrical heating elements. Because most instantaneous hot water heaters have little or no storage capacity, "on" and "off" switching controls tend to cause the temperature of the water being discharged from the vessel to oscillate above and below the desired set point temperature. Consequently, the temperature of the water being discharged can vary over a wide and possibly unacceptable range. Should the temperature of the water overshoot the set point temperature by a sufficient amount, the user may be exposed to excessively hot water.
It is the general object of this invention, therefore, to provide an improved water heating and delivery system for quickly and accurately heating water to a desired set point temperature.
It is another object of the present invention to provide a water heating and delivery system equipped with an improved control system for regulating the temperature of the water being discharged.